Design and Simulation of Two Stroke Engines

Chapter 7 - Reduction of Fuel Consumption and Exhaust Emissions
tion of fuel from the tank through the filter and pump to charge an accumulator at relatively
low pressure, some 6 or 7 bar, flow rapidly through a smaller-diameter acceleration pipe, and
the flow back to the tank if the solenoid valve is open. When the solenoid valve shuts, a highpressure
wave of some 25 bar is generated in the acceleration pipe and lifts the spring-backed
needle off its seat to give fuel injection. A picture of the ensuing fuel spray is shown in Plate
7.2 and Carson [7.28] describes the spray characteristics as lying between 15 and 38 pjn
SMD, over the full fueling range. A pressure regulator controls the fuel line pressure to a set
level and permits spillage back to the fuel tank. The damping valve is inserted into the circuit
to diminish the amplitude of the reflected pressure waves prior to the next injection signal.
One of the great advantages of this system is that it permits injection rates up to 6000 cycles
per minute and that it can operate at even higher pressure levels of up to 300 bar at the nozzle,
for use in compression-ignition engines [7.53].
DAMPING VALVE PRESSURE REGULATOR
FUELTANK
Fig. 7.49 Ram-tuned liquid fuel injection system.
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